As a member of the Teenage Exorcists, along with her close friends, Tess (18) and Savannah Scherkenback (21), Brynne travels the world slaying evil spirits with her crucifix and bible.

The trio, from Phoenix, Arizona, got together after they attended a sleepover, during which Miss Larson decided one of the other girls was possessed and convinced the two sisters to help her exorcise their friend.

After that night, the girls claim they decided to make exorcism ‘our life’s work’.

The comparisons with fictional characters such as Buffy the Vampire Slayer are inevitable and unsurprisingly the trio are now the subject of a new film causing quite a stir.

Documentary-maker Charlet Duboc followed the Teenage Exorcists as they toured impoverished mining towns in Ukraine, where exorcism is seen as the most effective way of combating addiction and the trauma of domestic abuse.

She said she found the experience unnerving, as much for the subject matter as the characters involved.

The film, created for Vice, depicts Brynne (the ‘enforcer’), Savannah (the ‘compassionate one’) and Tess (the ‘middle man’) as three girls so utterly convinced of their mission they appear unaware of how ridiculous some of their comments may sound to others.

At one point in the film, during a discussion on abstinence, they tell Duboc: ‘If you’re sleeping around, you’re getting other people’s demons. So many times we’ve dealt with men who have gone to prostitutes and they have gotten their demons.’

Duboc said: ‘The way they come across on camera is just the way they were when we turned off the camera, they never stopped the vacant smiling,’ the British film-maker said.

From left to right: Tess, Savannah Scherkenback and Brynne Larson (Picture: VICE Media)

‘They weren’t horrid, they weren’t unpleasant, they were just a bit creepy. It was a bit like talking to the Stepford Wives, I was like “where are the humans behind this?”’

Duboc said the belief in powers such as sexually transmitted demons and their daily fight against ‘the enemy’ (Satan) was unwavering in the face of her questioning.

‘Part of me thinks they know how funny it is and they know it’s going to hit the headlines, but someone told them that and that’s what they think – they really believe it, it’s bonkers.’

The irony of their actions was also lost on the impressionable demon hunters.

‘They’re young girls, they haven’t had a chance to develop outside their small home-schooled lives. Margaret Thatcher is their ultimate role model and there we were in a mining town. It was just bizarre,’ Duboc said.

Charlet Duboc conducting an exorcism herself (Picture: VICE Media)

The film, shot over five ‘awful’ days a few months ago, shows the three friends carrying out exorcisms on women who had been sexually abused as well as drug addicts told it represented their only hope at sobriety.

The New Generation Church in Ukraine has been able to capitalise on this need for exorcism, coupled with the rejection of the Orthodox church, and three young women flown in from the US are big news in these downtrodden regions.

One addict interviewed said he saw the girls as a mixture of the Spice Girls and ‘Buffy sisters’.

Duboc said: ‘It was depressing because I just didn’t see that exorcisms were going to help any of these people in the long term. It was a shame, these are lives being lived with the wool over their eyes.’

The group has also travelled to Russia and east and west Africa to carry out exorcisms.

Duboc’s opinion on the exorcisms was strengthened after she convinced the Teenage Exorcists and Brynne’s father Bob Larson, the controversial reverend who claims to have carried out 30,000 exorcisms during the last 30 years, to allow her to conduct one herself during the tour.

‘I knew I could do it, I knew I could get up on that stage and go through the motions,’ she said, revealing she later hated herself for taking part.

‘Ethically I wasn’t feeling great about it – but I thought if I can pull this off surely it shows this is all a bit symbolic and not got much to do with the devil.

‘The girls would argue that God worked through me. I just got on the stage and repeated lines with this woman screaming in my face. I went a bit numb while I was doing it, it was awful.’

Watch: Teenage Exorcists Part 1:

She said everyone they encountered was already a fan of Bob Larson and his teachings and ‘knew how to behave’. She added: ‘They knew how to manifest demons because they had seen it on YouTube’.

The Teenage Exorcists are a powerful vehicle for Larson, who controls the girls’ actions on and off the stage, but what will become of the young women if they start to outgrow his influence (they all want to go to university and become either lawyers or politicians)?

Watch: Teenage Exorcists Part 2:

And with Savannah Scherkenback already 21, Duboc questions how much bigger the real-life demon slayers can get.

For now though they remain determined to follow Rev Larson in his global quest, ‘curing’ the growing crowds that flock to them for salvation wherever they go.